[PATCH 3 of 4] py3: fully detach TextIOWrapper

[Yuya Nishihara]

On Wed, 04 Oct 2017 23:53:56 +0900, Yuya Nishihara wrote:
> # HG changeset patch
> # User Yuya Nishihara <yuya at tcha.org>
> # Date 1506923984 -3600
> #      Mon Oct 02 06:59:44 2017 +0100
> # Node ID fecbf1e8aa17474f448e126697fe287e44c92664
> # Parent  2b071e9303f748de41c02efdea158883d336224a
> py3: fully detach TextIOWrapper

Unfortunately, this broke test-py3-commands.t and it seems the Python
interpreter really hates detaching TextIOWrapper from stdio. So I'm going
to drop this and the next patch.